An erase function is used in non-volatile flash memory to restore the original state of a flash cell. Due to physical limitations of the erase operation, it takes a long time to complete the operation. The erase operation takes relatively longer than other main operations such as a page program. For example, where the erase time might be 1.5 ms, the page program time might be 25 us. With a block erase operation, an entire block is erased at once, a block consisting of a set of pages (rows). Because of this, block erase needs to backup the contents to another memory medium before erasing all contents in the selected block at the same time so as to enable some of the contents (certain pages) to be restored assuming some of the contents of the block should be kept. This requires another memory system to be incorporated in the same board or the same package to support the mentioned data restoration of flash memory. This increases the total system cost with flash memory and makes the data control more complicated.